mycanvas.java

图书管理系统：用户管理

import java.awt.*;
public class MyCanvas extends Canvas{
	static final long serialVersionUID=80;
	Dimension d;
	Image ii;  
	Graphics goff; 
	Font font = new Font("Helvetica", Font.BOLD, 15);
	FontMetrics fm;  //定义一个字体矩阵  
	String s1;
	String s2;
	int color1, color2;
	int dcolor1, dcolor2;
	MyCanvas(){
		setSize(350,40);
		d=getSize();
		setBackground(Color.BLACK); //设置背景色
		s1 = "邑大图书管理系统5.0 版权所有warcrafthero";      //所要显示的文字 
		s2 = "EMAIL:[e-mail] ";  //所要显示的文字
		color1 = 10;
		color2 = 245;
		dcolor2 = -2;
		dcolor1 = 2;
	}
	public void paint(Graphics g) {
		if (goff == null && d.width > 0 && d.height > 0) {
			//创建一个可以使用的双缓冲图像	
			ii = createImage(d.width, d.height);
			goff = ii.getGraphics();
		}
		if (goff == null || ii == null)
			return;
		goff.setFont(font);
		fm = goff.getFontMetrics(); 
		if (color1 < color2) {
			//设置颜色，并将文字画在屏幕上
			goff.setColor(new Color(color1 / 4, color1 / 2, color1));
			goff.drawString(s1, (d.width - fm.stringWidth(s1)) / 2,d.height / 2);
			goff.setColor(new Color(color2 / 4, color2 / 2, color2));
			goff.drawString(s2, (d.width - fm.stringWidth(s2)) / 2,d.height / 2);
		} else {
			goff.setColor(new Color(color2 / 4, color2 / 2, color2));
			goff.drawString(s2, (d.width - fm.stringWidth(s2)) / 2,
					d.height / 2);
			goff.setColor(new Color(color1 / 4, color1 / 2, color1));
			goff.drawString(s1, (d.width - fm.stringWidth(s1)) / 2,
					d.height / 2);
		}
		g.drawImage(ii, 0, 0, this);//
		//变换颜色
		color1 += dcolor1;
		color2 += dcolor2;
		if (color1 <= 3 || color1 >= 250)
			dcolor1 = -dcolor1;
		if (color2 <= 3 || color2 >= 250)
			dcolor2 = -dcolor2;
	}

}